Electric regulator



Dec. 19, 1922. 1,438946. R. D. CONWAY.

ELECTRIC REGULATOR.

FILED DEC.8, 1919.

Patented Dec. 19, 1922.

UiTED STATES PATENT oFFicE.

ROY ZD. CNWAY, 0F CHATHAM. NEVI JERSEY, ASSIGNOR TO WESTERN ELECTRIC COMPNY, ENCORPORATED, 0F NEW YRK, N. Y., A CORPORATION 0F NEW Yoan.

ELECTRIC REGULATOR.

Application led December 8, 1919.

To all zc/zom t may Concern.:

Be it known that l. Roy D. CONWAY, a

citizen ot the United States, residing at Chatham.. in the county of Morris, State of N ew Jersey. have invented certain new and useful Tmprovements in Electric Regulators, of which the following is a full, clear. concise, and exact description.

This invention relates to arrangements for regulating an electrical characteristic of a circuit such as the intensity of'current flowing therethrough. @ne of the objects of the invention is to provide a method and means for insuring a constant flow of current through a circuit. Another object consists in providing meansfor automatically increasing the resistance in a circuit whenever the current flow therethrough has a tendency to increase, and also vmeans for automatically reducing the resistance in said circuit as the current flow tends to de crease. Other objects of this' invention will appear in the detailed description to be given later.

It has often been found desirable to associate with a work circuit including trans` lating devices. such. for example, as a circuit including the filaments of vacuum tube repeaters. an, arrangement -for .regulating the current flow therethrough. This is because the voltage of the sourceJ supplying the electrical current may have a tendency to vary beyond the limits within which satisfactorv operation of the apparatus willresult. lAs it has been vfound that avvacuum tube repeater will give better service if the current fiow in its filament heating circuit remains constant. the regulating apparatus comprising this invention has been provided.

The preferred form of this invention comprises a voltmeter relay sensitive to slight variations in voltage, the winding gf which is connected to a source which supplies current for the work circuit. An increase in the voltage of this source will cause a circuit to be closed over the needle and one of the contacts of the voltmeter. thereby voperating a resistance varying mechanism to add a certain amount of resistance in` series with the winding of the voltmeter and in vthe work circuit. It the resistance thus Serial No. 343,3l8.

' varying mechanisnrwill continue to operate and will add further resistance units to the circuit including the voltmeterwinding and the work circuit until the increase in current flow has been counterbalanced and the needle returned to neutral position. If the current flow from the source decreases. a circuit is closed over the needle and another contact of the voltmeter which serves to operate the resist-ance varying mechanism to reduce the resistance in the voltmeter circuit and the work circuit in proportion to the decrease in voltage.

yIn the preferred form of this invention, thisresistance varying mechanism comprises two single motion step-by-step switches responsive to the volt'meter and controlling through a plurality of contact arms the amount of resistance in the voltmeter circuit and the work circuit. these switches is adapted to rotate its contact arms so as to increase the amount of resistance while the` other switch is adapted to rotate .its contact arms in such a direction as to decrease the amount of resistance. Means are also provided for insuring that the corresponding contact arms of the two switches will always be connected to the same points of the resistance so that there will be no break in the operation of the regulator for either increases or decreases in the voltage or current/of the work circuit.

This invention may now be. more fully understood from the following detailed de- Connected to a. battery 2 is the winding` of a voltmeter relay 4 which has a needle 5 located between two stationary contacts 6 and 7. Under the control of needle 5` and contact 6 is a relay 8 which has under its control a magnet 9 for operating the step- One ot' ping mechanism" for contact arms 10, 11 and 12. Thesethree contact arms if desired may be mounted on a common shaft. rlfhe step-by-step mechanism for vcontact arms 10, 11 and 12 is not shown in the drawlng, but may ber of lany suitable type, and may comprise for example a ratchet wheel mounted on the shaft and controlled by a stepping pawl adjacent magnet 9. rfhese contact arms should be controlled 'by their stepping mechanism in su'ch a manner as to `cause t-hem to 'rotate in a counter clockwise dirertion. rlhe position of contact arm 10 determines the effective amount of r sistance 16 which is `connected in circuit with the winding of voltmeter relay 4 vfor increasing values of the resistance. Contact arm 12 serves to determine the effective amount of resistance 17 which is included in the heating circuit for filaments 18 of the vacuum -tube repeaters 19, for increasing values of the reslstance. rlhe function of contact arm 11 will be described later.

Ibe cont-rolled by their stepping mechanism in such' a manner as to cause them to rotate in a counter-clockwise.direction. Contact arm 22 serves to control the amount of resistance16 in circuit with the voltmeter relay winding for decreasing values of the resistance. Similarly contact arm 24 serves to control the amount of resistance 17 in the work circ-uit for decreasing values of the resistance.

rlFhe method of operation of the circuit arrangement of this invention may now be explained as follows: Assume, with contact arms 10, 11 and 12 and'22, 23 and 24 in the-positions shown, that battery,2 is supplying normal value of heating current for the filaments 18. rlFhe needle 5 of voltmeter 4 will, therefore, be in neutral position. With contact arm 12 on contact 46 a heating circuit for cathodes 18 may be traced as follows: from ground, battery, conductor 51, resistance 17, conductor 27, cathodes 18v to ground. Since in the opera-tionv of the circuit arrangement, either relay 8 or 2O is always energized, another heating circuit for the filaments 18 is provided as follows: from ground, battery 2, conductor 32, movable `contact 35, conductor 50, contact arm 12 to contact 46 or from ground and battery, conductor 54, movable contact 55, conductor 56, contact arm 24-to conductor 27 and cathodes 18 to ground. rllhe heating current supplied to the cathodes V18, therefore, consists of two components, one fed to the cathodes through conductor 51 and all of resistance 17, the other component being fed through either conductor 50 o r 56 to the cathodes.

Suppose for example that the amount of heating current sup-plied to the cathode should tend to increase beyond its normal value due to a change in the voltage of source 2. 'llhis increase of the voltage of source 2 will cause'needle 5 to be deflected to the right and close the following circuit: from.

ground, through the motor-driven interrupter 29, needle 5, contact 6, conductors 30, 31, winding relay 8, conductor 32 to battery and ground. r1`he closing of this circuit will cause relay 8 tc become energized, there by pulling up its movable contacts 33, 34, 35 and 36. rllhe pulling up. of movable' contact 34 will cause relay 8 to be locked up over the following circuit: from ground and battery, conductor 32, winding relay 8, conductor 31, movable contact 34,' conductor 38, and movable contact 39 te ground. 5 The pulling upl of movable Contact 36 closes the following circuit, from ground, interrupter 29,` needle 5, contact 6, conductors 30, 42, and 43, winding relay 9 to battery and ground. rThe closing cf this circuit will cause interrupter 29 to send out impulses over thisn circuit. The first impulse produced by interrupter 29 will cause' relay 9 te operate the step-ping mechanism of contact arms 10, 11 and 12 so 'as to move them ene stepl ina counter-clockwise direction. Uontactkarms 10, 11 and 12 will, therefore, be mo-ved from contacts 44, 45 and 46 to contacts 58,59 and 60. rlhe moving of contact arm 12 from contact 46 to Contact 58 will increase 'the resistance in circuit with cathodes 18 and conductor 59 by an amouit equal te that part of resistance 17 which is located between the two contacts. 'llhe amount of heating current supplied to cathodes 18 through conductor 50 will, therefore, be decreased. Due tcthe moving of contact arm 10 from contact 44 to contact 60 the supply circuit fo-r voltmeter 4 may now be traced as follows: from ground and battery 2, winding of voltmeter 4, conductor 65, that part of resistance 16 which is included between contact 44 and contact 60, contact arm 10, conductor 48, movable contact 33 to ground. rlFhe moving of contact arm 10 from Contact 44 to contact 60 has, therefore, increased the amount of resistance in the voltmeter circuit. 1f the amount of resistance added to the filament circuit and to the voltmeter circuit is sui'licient to compensate for the increase in voltage of source 2, needle 5 will return to neutral position. Relay 8, however, will remain energized on account of its being locked Pup over movablelll Ill

still traced over the closed contacts of relay 8, as described above. lt, as just assumed, the addition of the two elements of resistance to the filament circuit .and theyoltmeter circuit are sufficient to compensate, needle 5 will return to neutra-l position beore sm'iicient time `has elapsed Jor intera rupter 29 to send a second impulse to relay 9 for stepping the mechanism a second time. Contact arms 1G, 11 and 12 will, therefore, remain on contacts 58, `59 and 60.

its noted above, either relay 3 or 29 is always energized in the operation ot this circuit arrangement., i Prior to the energization or' relay 3 described above and while relay 2O was therefore energized, the following circuit Was completed over the contacts of relay 9: trom ground, battery, winding of relay 9, conductor 43, movable contact 36, conductor 98, movable contact 66 and resistance 67 to ground. Although this circuit Was closed, battery 2 was prevented from energizing relay 9 because relay 9 Was shortcircuited at the same time by the following connection: battery 2, conductor 54, contact 69 of energized relay 20, conductor 70, contact 71, conductors 72, 7 3, contact 6G, conductors 98 and 43 to Winding of relay 9. Since the battery 2 shown adjacent relay 9 is the same battery as that shown adjacent relay 20, (the battery being shown at vz rious places in the drawing as a matter of convenience only), it follows that the connection just. traced through conductors 43, 98, T2 and 70, acts as adirect short-circuit across relay 9 and thereby prevents its operation. lith relay 20 energized, relay 2l will also not be energized because its only connection to ground is through conductors 68 and 99, through the contacts ofvoltmeter relay 4. A similar condition exists when, in the operation ofthe circuit arrangement, relay 20 is deenergized and relay 8 isenergized. In this last condition, the only ener- ,gizing circuitI for relay ..9 is through con.- ductors 43, 42 and 30V to ,the contacts of the v'oltmeter relay 4 so that relay 9 will operate only upon the deflection of'the needle 5 to the right. Although with relay 2O deenergized. the path from ground, battery,

cuit, relay 21 ivill continue to operate the` steppingmechanism for contact arms 22, 23 and 24 until these contact arms are connected to contacts '56, TT and i3. fis soon as contact arm 23 reaches contact 7?, the relay' 21 will cease operating since it will be connected `through conductors 78., 93 and 32 to battery 2, thereby reestablishing the shortscircuiting above described.

lf, however, the amount of resistance that has been added to the voltmeter circuit and the filament circuit is not sufficient to compensate for the increase in voltage ot' source 2, needle 5 will remain deflected to the right and the interruptcr 29 will send a second impulse to relay 9. thereby causing this relay to rotate contact arms 10, 11 and 12 one step farther in a counter-clockwise direction. The moving ot' cont-act arms 10 and 12 Will add a. 'second element ot resistance to both the voltmeter. circuit and the filament circuit by circuits previously traced. The moving of' contact arm 11 from Contact 59 on to the next contact in order will remove the neutralizing` connection for relay 21, and allow it to step around cont-act arms 22. 23 and 24, until contact arm 23 is on such a contact as to reestablish the neutralizing action. If the addition of this second element of re sist-ance to the voltmeter circuit and the Qvorl; circuit is sufficient to counterbalance the increase in voltage of source 2. the needle 5 Wrillreturn to neutral position before intel'- rupter 29 has had sufficient time -to send out a third impulse to relay 9.

If'. however. the second element ot resistance is not suflicient to compensate for the increase in voltage, it follows that needle 5 winding of relay 20, conductors'GS. 70, oon-Will remain deflected to the right. and iutertact T1, resistance 74 to ground is closed, the closing ot this circuit- Will not operate relay 21 sincel the relay is short-circuited with respect to battery '2 by conductors 68, To. 72. A73. 9e, 32m battery 2.

Keeping in mind. the fact that relay 21 is temporarily short-circuited when relay 20 is deenergized and relay 8 is energized, it will be seen that as soon as interrupter 29 has sent. out an impulse over the previously traced circuit to step the contact arm 11 from contact 45 to contact 59. the short-circuiting connection for relay 21 through the energized contacts of relay 8 will be broken rupter 29 will continue to send out energizing impulses to relay 9. until lrelay 9 has stepped around contact arms 10. 11 and 12 far enough to add to the work circuit and the voltmeter circuit a sufficient number of the elementsyof resistances 16 and 17 to com-` pensate for the increase in voltage. Every change in the position of contact arms 10. 1v1 and 12 will cause contact arms 22. 23 and 24 t0 change their positions so that when the compensation for the increase of voltage for soulce 2 has been obtained. contact arms 10` 11 and 12 and 22. 23 and 24 will be resting on corresponding contacts. Suppose, for exing current component for cathodes 18 may' ample, that in order to cempensate for the increase in voltage, contact arms .10, 11 and 12 were moved to contacts 80, 81 and 82, respectively. With contact arms 10, 11 and 12 in this position, contact arms 22, 23and 2t will be located on contacts 83, 84C and 85, respectively. With the six contact arms on these last-mentioned contacts, supposev that the heati-ng current for cathodes 18 is decreased in value due to the decrease in voltage of battery 2. Needle 5, which before the decrease in voltage was in neutral condition, will now be deflected on the left and close the following circuit: ground, interrupter 29, needle 5, contact 7, conductors 86 and 87 winding relay 20, conductor 5d to battery and ground. 'llhe closing of this circuit will energize relay 20 to pull up its movable contacts. The pulling up of contact -39 will break the locking circuit for relay 8, which `was previously traced as follows: from ground, battery 2, conductor 32, winding vrelay 8, conductor 31, movable contact 34;-, conductor 38, movable contact 39 to ground. rlhe deenergizatiton of relay 8 will cause movable contact 33 to fall back land close the following locking circuit for relay 20: from vground, battery 2, conductor 5t; winding relay 20, conductor 87, movable contact88, conductor 89, movable Contact 33 to ground. Due tothe pulling up of movable contact 69, interrupter' 29 will now send an energizing impulse over the following circuit to relay 21: from ground, interrupter 29, needle 5, contact 7, conductors 86,99, and 68, winding relay 21 to battery and ground. rllhe closing'.

of this circuit will cause relay 21 to operate the stepping mechanism of contact arms 22, 23 and 24: one step in a counter-clockwise direction, so that they now rest on contacts 90, 91 and 92,4respect1vely. When the7 contact' arm 24 was on contact 85, the variable heatbe traced through the following circuit: from ground, battery 2, conductor 54h-movable contactl 55, conductor 56, contactarmv 24, contact 85, that part of resistance 17 located between contact 85 and conductor'27, cathodes 18 to ground. its soon, however, as contact arm 24 has been moved to contact 92, it is evident that the resistance in the oircontact arm 22 from contact 83 to contact 90,

the amount' of resistance inf the voltmeter circuit has been decreased by the amount of resistance located between these two contacts. With the moving of contact arms 22,

rection, relay 9 will be operated to move contact arms 10, 11 and 12 until they rest on corresponding contacts. llf thev decrease in amount of resistance in the work circuit and thevoltmeter circuit is sullicient to counterbalance the decrease in the voltage of source 2, needle 5 will return to neutral position before interrupter 29 has had suflicient time to send out a second energizing impulse for relay 21. lttelay 20, however, will remain locked up over the circuit previously traced.

lf, however, the decrease in the amount of resistance in the voltmeter circuit and the work circuit is not sufcient to counterbalance the decrease in voltage of source 2, needle 5 will remain deflected to the left, sothat interrupter 29 will send a second impulse to energize relay 21 for stepping around contact arms 22, 23 and 211 and ad ditional step in the counter-,clockwise direction, thereby producing a` second decrease in the amount of resistance in the work circuit and the voltmeter circuit. lf this second decrease in the value of the resistance is not sufficient to counterbalance the delay 9 to step contact arms 10, 11.` and 12 to corresponding positions so that contact armsv Every change in the position f 10, 11 and 12 will be ready at any time to f increase the value of the resistances beg-in'- ning at the value of the resistances last determined by contactarms 22, 23 and 24.

Contact arms 22, 23 .and 2a will, therefore,

take care of decreases in voltage of battery sistance 16 and 17 which hasvbeen deterofcontact arms.

lt will generally be found preferably to adjust the circuits so thatwith normal voltage from source2, the contact arms will be connected approximately to the middle of the resistances, thereby allowing the regulator to compensate for a large increase as 4mined by the last movement of either set lwell as decrease in voltage.

y Although magnets '9 and 21 are shown controlling contact arms for only one filament heating circuit, it is evident that these magnets maycontrol a plurality of sets of such arms in a similar manner for controlling a plurality of heating circuits.

lin the drawing only ten contacts v been illustrated for each contact arm. lt is evident, however, that any desired numhave value ot resistances 16 and la'.

bei ot contacts may be employed for each contact arm so as to give any desired graduation in the step-by-step variation ot' the lt is also evident that other modifications may be made inthe circuitlarrangement above described Without departing in anyWise t'rom the spirit of this invention as defined in the appended claims.

llvhat is claimed is:

l. ln an electric system. av'ork circuit. a solenoid responsive to a condition of said Work circuit. a variable impedance in said Work circuit. means responsive to said solenoid for increasing the value of said impedance.l means responsive to said solenoid tor decreasing the value ot' said impedance. contacts connected to a plurality ot points on said impedance individual to said iii-st means and contacts connected to a plurality or" points on said resistance individual to said second means.

2. ln an electric system. a'Work circuit. a source ot voltage in said circuit, and means responsive tothe .voltageot said source for holding substantially constant the current in said circuit. said Vmeans comprising a solenoid responsive to the voltage of said source. a variable impedance in said Work circuit. magnetic means responsive to said solenoid for increasing the value of said impedance. magnetic means responsive to said solenoid for decreasing the value of said impedance. contacts connected to a plurality ot points on said impedance individual to said first magnetic means. and contacts connected to a plurality of points on said impedance individual to said second magnetic means.

3. ln an electric system a Work circuit. a solenoid responsive to a conditionv of said Work circuit. a variable impedance, means responsive to.. said solenoid for increasing` the value of said impedance. and means responsive to said solenoid for decreasing the value. of said impedance. each ot said means at times being responsive tothe other of said means.

9;-, ln an electric system a Work circuit. a solenoid responsive to a condition ot said Work circuit. a variable impedance in said Work circuit. means responsive to said solenoid for increasingthe value otx said impedance. means responsive to said solenoid for decreasing the value of said impedance, each of said means comprising a movable contact arm adapted to be connectedto a plurality of points on said impedance.

5. In an electric system. a Work circuit. a solenoid responsive to a condition of said Work circuit. a variable impedance in said Work circuit.. magnetic means responsive to said solenoid for increasing the value of said impedance. magnetic means responsive to said solenoid for decreasing the value of said impedance. each ot said magnetic, means comprising circuitclosing means adapted to be connected to a plurality of points on said impedance. one ot' said magnetic means being responsive at times to the other of said means.

6. ln an electric system. a source of voltage. a Work circuit comprising said source. a solenoid responsive to a condition ot' said Work circuit. a variable impedance in said Work circuit. a set of contacts connected to a plurality of points on said impe-dance. a second set of contacts connected to a plurality of points on said impedance. circuitclosing means cooperating With one set of said contacts. a second circuit-closing means cooperating With the second set ot said contacts. magnetic means responsive to said solenoid for operating one of said circuitclosing means for a change in voltage of said source. and magnetic means responsive to said firstmagnetic mea-ns Afor operating said second circuit-closing means.

ln an electric system a source of voltage. a Work circuit comprising said source. a solenoid responsive to a condition of said Work circuit. a variable impedance in said Work circuit. a set of contacts connected to a plurality otl points on said impedance. a second set of contacts connected to a plurality of points on said impedance. circuitclosing means cooperating With one set of said contacts. a second circuit-closing means cooperating With the second set of said contacts. magnetic means operating one of said circuit-closing means `for an increase in voltage. magnetic means operating the other of said circuit-closing means for a decrease in voltage. only one of said magnetic means at one time being responsive to said solenoid. the other of said magnetic means atsuch a` time-being responsive to said other magnetic means.

8. In an electric` system. a source of voltage. a Work circuit comprising said source. a solenoid responsive to a condition of said Work circuit. a variable impedance in said Work circuit. a set of contacts connected to a plurality of points on said impedance. a second set of contacts connected to a plurality of points on said impedance. circuitclosing means cooperating With one se-t of" said contacts. a second circuit-closing means cooperating With the second set of said con- 7 9. In anelectric system i Work circuit., a

llt)

source of voltage in said circuit, a volt-meter responsivelto a condition ot said work circuit, means tor changingthe calibration of said voltmeter when changes in said source occur, a variable impedance in said lworlr circuit, meansresponsive to said voltmeter for increasing the value of said impedance, means responsive to said voltmeter for decreasing the value ot said impedance, each ot said means at times being responsive to the other ot said means.

10. ln an electric system, a work circuit, a source :oi2 voltage in said circuit, a `voltmeter responsive to a condition of said circuit, a variable impedance in circuit with said voltmeter, a variable impedance in said work circuit, two sets ot contacts connected to a plurality of points on each of said impedances, circuit-closing means cooperating with two sets 'oil' said contacts, a second circuit-closing means cooperating with the other two sets ont said contacts, magnetic means responsive to said voltmeter for operating said first circuit-closing means, and

magnetic means responsive to said voltmeter 'lior operating the other of said circuit-closing means.

1l, ln an electric system, a worlr circuit, a source ot voltage in said circuit, a voltmeter responsive to a condition or said circuit, a variable impedance in said work circuit, a set ot contacts connected to a plurality ot points on said impedance, a second set of contacts connected to a plurality ot points on said impedance, circuit-closing means cooperating with one set ot said contacts, a second circuit-closing means cooperating with said second set of contacts, and magnetic means responsive to a condition ot said worlr circuit tor operating both ot said circuit-closing lmeans when a change in the condition of said work circuit `occurs.

l2. ln an electric. system a work circuit, a source of voltage, a solenoid responsive to a condition ot said worlr circuit tor regulating said worlr circuit,I a variable `impedance in said worlr circuit, a rotary' switch lor varying the eidective value of said impedance tor an increasevin voltage in said source, a second rotary switch :tor varying the effective value oit said impedance tor a decrease in voltage ot said source, and inagnetic means responsiveto said solenoid tor operating said switches when a change in voltage occurs. v

13. ln an electric system awork circuit, a source ot voltage in said circuit, a solenoid responsive to a condition ot said worlr circuit, a variable impedance in said work circuit, a rotary switch tor varying the ellective amount otsaid impedance when an increase in voltage occurs, a second rotary switch for varying the edective amount ot said impedance .when apdecrease in voltage insonne occurs, magnetic means responsive to said solenoid for operating one ot said switches, and magnetic means responsive to' said solenoid tor operating the other of said switches, only one ot said magnetic means at one time being vresponsive to said solenoid, the other of said magnetic means at such a time being responsive to said tirstmagnetic means.

lll. ln an electric system, a worlr circuit, a source of voltage in said circuit, means responsive to the voltage in said circuit tor regulating the current in said circuit, said means comprising a voltmeter responsive to the voltage ot said circuit, a variable resistf ance in said worlr circuit, 'a second variable resistance in circuit with said voltmeter, aA

rotary switch tor varying the etlective amounts ot said impedances when an increase involtage occurs, a second rotary switch tor varying' the amount of said iinpedances when a decrease in voltage occurs, magnetic means under the control orp lsaid voltmeter for operating said switches, each oil said switches having ya contact arm individual to each of said resistances, a set ol contacts connected to a plurality ot points on each ot said impedances cooperating with each ot said contact arms, a third contact arm on each ot said switches, contacts cooperating with each ot said third arms, corresponding contactsy for said third arms being electrically connected, and'connections whereby the operationv ot one of said switches operates said other switch to move Contact arms until its third contact arm is on that cooperating contact which is electrically connected to the contact on which the third 'arm oi said othenyswitch rests.

l5. ln an electric system, a work circuit, a variable impedance and a' 'source ot voltage insaid work circuit, a control element responsive to a condition oii said worlr circuit, a variable impedance in circuit with said control element, and a rotary switch responsive to said control element 'lor varying the value ot said impedance.

16. ln an electric system, a worlr circuit, a variable impedance and current supplyjing means in said work circuit, a voltmeter responsivej to the current in said worlr circuit, a second variable impedance in circuit with the win-ding of said voltmeter, and a rotary switch responsive to said voltmeter tor simultaneously varying the etlective values ot said impedances. 17. lin an electric system, a work circuit, current Supplying means and a regulating element in said'worlr circuit, a plurality oit switches each adapted to vary the-effective value oit said regulating element, a control element responsive to a condition ot said worlr circuit tor controlling the motion ot one oil said switches and icr subsequently moving another thereof.

llt)

Maaate 18. an electric system, a work circuit, current supplying means and a variable impedance `-for said Work circuit, a. pluralityv ot switches each adapted to vary the effectivevalueot said` impedance, a solenoid responsive to the current ofsaid work circuit for cont-rolling the motion ot one of said switches and for subsequently controlling the motion of another thereof for a single change in the current ot said work circuit. Y

19. 'in an electric system, a work circuit, a regulating element and current supplying means tor said work circuit, a cont-rol element responsive to a condition of said work circuit, a set of switches responsive to said control element for cont-rolling said regulating element for increases in a condition ot said work circuit and a second set of switches responsive to said cont-rol element ment tor decreases in al condition ot' said work circuit.

20. ln an elect-ric syst-em., a work circuit, a plurality of switching mechanisms. each having an active contact and a plurality of passive contacts, connections between corresponding passive contacts of said mecha.- nisms, means responsive to a condition ot said work circuit for causing the active contact-'oit any one of said mechanisms to distinguish one or" its associated passive convtacts. and means responsive thereto for causing the active contact ot' another of said mechanisms to hunt and rest on that one ot its associated passive contacts which is connected to the passive contact on which said first mentioned active contact rests.

2l. ln combination a work circuit, a regulating element in said work circuit, a one-way rotary switch tor increasing the value ot said regulating element and means for decreasing the value ot said regulating element.

Q21. lin combination a work circuit, a regulating element in said work circuit, a

one-way rotary switch adapted to produce said work circuit.

tor controlling said regulating ele-` 24. ln combination a work circuit, a regulating element in said work circuit, a one-way rotary switch adapted to increase the eective value ot said regulating element, a second one-way rotary switch adapted to decrease the effective value ot said regulating element and means responsive to a condition ot said work circuit for controlling said switches.

25. lin combination a work circuit, a regulating element in said work circuit, a row of stationary contacts'arranged in the form Ot' a portion of a circle, a movable switch member adapted to cooperate with said contacts. means responsive to a condition oit said work circuit for controlling a position ot said movable member, a second row ot contacts corresponding to the tirst row, a. second movable member cooperating with said second row of contacts and means operating on the motion of said first movable member for causing said second movable member to nd a contact corresponding to the contact cooperating at any particular instant with said first movable member.

26. ln combination a work circuit, a regulating element adapted to be placed to a varying degree in said circuit and a plurality of controlling means tor said element, one of said means being arranged for progressive operation in an opposite sense to another of said means.

27. In combination a work circuit, a regulating element in said work circuit, a solenoid having a stationary contact and a movable contact and responsive to a condition of said work circuit, a relay having a movable contact and responsive to said solenoid for controlling the effec-tive value ot said regulating element for a change in the condition of said work circuit, a. second relay having a movable contact and responsive to said solenoid for controlling the effeet-ive value of said element for an opposite change in said work circuit, and an interiupter operatingA over the contacts of said solenoid for controlling the energization of said relays.

28. In combination a work circuit, a. regulating element in said work circuit, a one-way rotary switch adapted to increase the value ot said element, al second one-way rotary switch adapted to decrease the effective value of said element, electro-magnetic means for controlling the position of said switches and an interrupter for periodically energizing one of said means.

In witness whereof, I hereunto subscribe my name this 4th day of December, A.

. nor D. CONWAY. 

